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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

The cosmic radiation in the heliosphere at successive solar minima

Cosmic ray observations at 1 AU are compared for the last three solar minimum periods along with the 1977/1989 and 1987 Pioneer 10 and Voyager 1 and 2 data from the outer heliosphere. There is good agreement between the 1965 and 1987 Galactic cosmic ray H and He spectra at 1 AU. Significant and complex differences are found between the 1977/1978 and 1987 measurements of the Galactic and anomalous cosmic ray components at 1 and 15 AU. In the outer heliosphere there are negative latitudinal gradients that reach their maximum magnitude when the inclination of the outer heliosphere current sheet is at a minimum. The radial gradients decrease with heliocentric distance as about 1/r exp 0.7 and do not differ significantly at the successive solar minima. The measured radial and latitudinal gradients are used to estimate the particle transport parameters in the outer heliosphere. Using the local interstellar He spectrum of Webber et al. (1987), it is estimated that the modulation boundary is of the order of 160 AU.

Mcdonald, Frank B.↗
NASA NTRS1974

The abundances of nuclei in the cosmic radiation

The relative abundances are treated as a consequence of processes in cosmic ray transport occurring during passage of the radiation through interstellar material at high velocity. Some of the subjects mentioned are nuclear fragmentation and the production of secondary nuclei, nuclear reactions, energy loss and nuclear decay, ionization, the range-energy relation and propagation variables, capture and loss of electrons, the propagation of nuclei, the transport equation, equilibrium solutions, energy-dependent path length distribution, exponential path length distributions, discrete spectra, sources, supernovae, and the origin of the abundances. The connection between the space-time features of the sources, the material traversed, and the effects of magnetic fields is established by describing the particle-field interaction as a diffusive or random-walk process.

Reames, D. V.↗
NASA NTRS2004

The ALTEA/ALTEINO projects: studying functional effects of microgravity and cosmic radiation

The ALTEA project investigates the risks of functional brain damage induced by particle radiation in space. A modular facility (the ALTEA facility) is being implemented and will be operated in the International Space Station (ISS) to record electrophysiological and behavioral descriptors of brain function and to monitor their time dynamics and correlation with particles and space environment. The focus of the program will be on abnormal visual perceptions (often reported as "light flashes" by astronauts) and the impact on retinal and brain visual structures of particle in microgravity conditions. The facility will be made available to the international scientific community for human neurophysiological, electrophysiological and psychophysics experiments, studies on particle fluxes, and dosimetry. A precursor of ALTEA (the 'Alteino' project) helps set the experimental baseline for the ALTEA experiments, while providing novel information on the radiation environment onboard the ISS and on the brain electrophysiology of the astronauts during orbital flights. Alteino was flown to the ISS on the Soyuz TM34 as part of mission Marco Polo. Controlled ground experiments using mice and accelerator beams complete the experimental strategy of ALTEA. We present here the status of progress of the ALTEA project and preliminary results of the Alteino study on brain dynamics, particle fluxes and abnormal visual perceptions. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

manned↗
NASA NTRS1986

Lead, platinum and other heavy elements in the primary cosmic radiation: HEAO-3 results

An observation of the abundances of cosmic-ray lead and platinum-group nuclei using data from the HEAO-3 Heavy Nuclei Experiment (HNE) which consisted of ion chambers mounted on both sides of a plastic Cherenkov counter (Binns et al., 1981) is reported. Further analysis with more stringent selections, inclusion of additional data, and a calibration at the LBL Bevalac, have allowed the determination of the abundance ratio of lead and the platinum group of elements for particles that had a cutoff rigidity R(c) 5 GV. The observed ratio for Pb/Pt is distinctly lower than that predicted by any of the standard models for cosmic ray sources. It is possible that the difference is not an indication that the cosmic ray source composition is greatly different from that of the solar system, but rather that there is less Pb in the solar system and in the r-process than is assumed in the standard models.

Waddington, C. J.↗
NASA NTRS1985

Lead, platinum, and other heavy elements in the primary cosmic radiation - HEAO 3 results

An observation of the abundances of cosmic-ray lead-group and platinum-group nuclei is reported, using data from the HEAO 3 Heavy Nuclei Experiment. From an analysis of 580 days of exposure, 322 nuclei were selected with reasonable charge resolution, E at least 1.3 GeV/nucleon and Z at least 50. The data show a defined abundance peak in the 'platinum' region (Z from 74 to 80), a small abundance of 'lead' (Z from 81 to 83), and a significant number of 'secondary' nuclei in the range of Z between 62 and 73. Possible explanations are offered for the deduced ratio in space of 0.25 plus or minus 0.09 for 'Pb/Pt' being distinctly lower than that predicted by any of the standard models for cosmic-ray sources and propagation effects.

Binns, W. R.↗
NASA NTRS1985

An update on the correlation between the cosmic radiation intensity and the geomagnetic AA index

A statistical study between the cosmic ray intensity, as observed by a neutron monitor, and of the geomagnetic aa index, as representative of perturbations in the plasma and interplanetary magnetic field in the heliosphere, has been updated to specifically exclude time periods around the reversal of the solar magnetic field. The results of this study show a strong negative correlation for the period 1960 through 1968 with a correlation coefficient of approximately -0.86. However, there is essentially no correlation between the cosmic ray intensity and the aa index for the period 1972-1979 (i.e. correlation coefficient less than 0.16). These results would appear to support the theory of preferential particle propagation into the heliosphere vis the ecliptic during the period 1960-1968 and via the solar polar regions during 1972-1979.

Shea, M. A.↗
NASA NTRS2015

NASA Galactic Cosmic Radiation Environment Model: Badhwar-O'Neill (2014)

The Badhwar‐O'Neill (BON) Galactic Cosmic Ray (GCR) flux model is used by NASA to certify microelectronic systems and in the analysis of radiation health risks for human space flight missions. Of special interest to NASA is the kinetic energy region below 4.0 GeV/n due to the fact that exposure from GCR behind shielding (e.g., inside a space vehicle) is heavily influenced by the GCR particles from this energy domain. The BON model numerically solves the Fokker‐Planck differential equation to account for particle transport in the heliosphere due to diffusion, convection, and adiabatic deceleration under the assumption of a spherically symmetric heliosphere. The model utilizes a GCR measurements database from various particle detectors to determine the boundary conditions. By using an updated GCR database and improved model fit parameters, the new BON model (BON14) is significantly improved over the previous BON models for describing the GCR radiation environment of interest to human space flight.

O'Neill, P. M.↗
NASA NTRS2015

NASA Galactic Cosmic Radiation Environment Model: Badhwar - O'Neill (2014)

The Badhwar-O'Neill (BON) Galactic Cosmic Ray (GCR) flux model has been used by NASA to certify microelectronic systems and in the analysis of radiation health risks for human space flight missions. Of special interest to NASA is the kinetic energy region below 4.0 GeV/n due to the fact that exposure from GCR behind shielding (e.g., inside a space vehicle) is heavily influenced by the GCR particles from this energy domain. The BON model numerically solves the Fokker-Planck differential equation to account for particle transport in the heliosphere due to diffusion, convection, and adiabatic deceleration under the assumption of a spherically symmetric heliosphere. The model utilizes a comprehensive database of GCR measurements from various particle detectors to determine boundary conditions. By using an updated GCR database and improved model fit parameters, the new BON model (BON14) is significantly improved over the previous BON models for describing the GCR radiation environment of interest to human space flight.

Golge, S.↗
NASA NTRS1982

The abundance of the actinides in the cosmic radiation as measured on HEAO 3

The HEAO 3 detector of heavy cosmic-ray nuclei has observed one possible actinide nucleus and some 100 nuclei of the platinum-lead group of elements. The resulting upper limit of 3% for the abundance ratio of actinides to platinum-lead nuclides is significantly lower than previous results from other observations. This new limit is inconsistent with freshly synthesized, pure r-process sources for cosmic-ray nuclei in this charge interval but is consistent with a source having a composition similar to the solar system, or to aged r-process material. We observe no events with a charge greater than 96.

Binns, W. R.↗
NASA NTRS1985

Lead, platinum, and other heavy elements in the primary cosmic radiation: HEAO-3 results ssc wg032961 cb553097

An observation of the abundances of cosmic-ray lead and platinum-group nuclei using data from the HEAO-3 Heavy Nuclei Experiment (HNE) which consisted of ion chambers mounted on both sides of a plastic Cerenkov counter is reported. Further analysis with more stringent selections, inclusion of additional data, and a calibration at the LBL Bevalac, have allowed obtaining the abundance ratio of lead and the platinum group of elements for particles that had a cutoff rigidity R sub c 5 GV.

Waddington, C. J.↗